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This study investigated alkaline phosphatase (APase) activity and dissolved organic and inorganic phosphorus utilization by the harmful dinoflagellate Gymnodinium impudicum (Fraga et Bravo) Hansen et Moestrup isolated from the South Sea of Korea. Under conditions of limited phosphorus, observation of growth kinetics in batch culture yielded a maximum growth rate (μmax) of 0.41 /day and a half saturation constant (Ks) of 0.71 μM. In time-course experiments, APase was induced as dissolved inorganic phosphorus (DIP) concentrations fell below 0.83 μM, a threshold near the estimated Ks; APase activity increased with further DIP depletion to a maximum of 0.70 pmol/cell/h in the senescent phase. Thus, Ks may be an important index of the threshold DIP concentration for APase induction. G. impudicum utilizes a wide variety of dissolved organic phosphorus compounds in addition to DIP. These results suggest that DIP limitation in the Southern Sea of Korea may have led to the spread of G. impudicum along with the harmful dinoflagellate Cochlodinium polykrikoides in recent years. 相似文献
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Hydrogeochemical interpretation of water seepage through a geological barrier at a reservoir boundary 
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下载免费PDF全文 A geological barrier such as a mountain ridge surrounding a large reservoir generally plays some part in preventing water leakage from the reservoir, but water flows out naturally according to the hydraulic gradient because the reservoir water level is typically higher than that outside. The hydrogeological, geochemical, and isotopic properties of water in the Daechung Dam area were analysed to characterize the source and the phenomenon of the groundwater flowing through the geological barrier. Our geochemical analysis showed that the concentrations of anions and cations tended to increase, due to the longer residence time of the water, as the distance between the sampling site and reservoir increased. Elevation differences (calculated using oxygen and hydrogen isotopes) between the highest and lowest sampling sites ranged between 350 and 420 m based on the altitude effect on isotope concentration, but the actual difference was only 35 m. These results, including analysis of the rate of water seepage from the reservoir (ca. 2.3% to 14.4% of natural recharge), indicate the possibility that groundwater in the study area originated from reservoir water that was derived from upstream water and rainfall in the high mountainous area of the upper watershed. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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Seung-Woo Lee Jan Kouba Bob Schutz Do Hyeong Kim Young Jae Lee 《Journal of Geodesy》2013,87(10-12):923-934
This paper addresses real-time monitoring of the precipitable water vapor (PWV) from GNSS measurements and presents some results obtained from 6-month long GNSS PWV experiments using international and domestic GNSS networks. In the real-time GNSS PWV monitoring system a server/client structure is employed to facilitate formation of PWV networks and single-differenced GNSS measurements are utilized to mitigate errors in GNSS satellites’ orbits and clocks. An issue relating to baseline length between the server and clients is discussed in detail and as a result the PWV monitor is configured to perform in two modes depending on the baseline length. The server estimates sequentially the zenith wet delay of the individual stations, which is then converted into the PWV of the stations. We evaluate system performance by comparing the real-time PWV solution with reference solutions including meteorological measurements obtained with radiosondes and deferred-time precision GNSS PWV solutions. Results showed that the standard deviation of difference between the real-time PWV and the reference solutions ranged from 2.1 to 3.4 mm in PWV for a 6-month long comparison, which was improved to 1.4 to 2.9 mm by reducing comparison period to 20 days in winter. 相似文献
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Gwang H. Lee Dae C. Kim Mi K. Park Soo C. Park Han J. Kim Hyeong T. Jou Boo K. Khim 《Island Arc》2010,19(1):71-85
The Korea Strait shelf mud (KSSM) (Nakdong River subaqueous delta) is the most conspicuous Holocene sedimentary feature in the inner shelf off southeast Korea. Analysis of multi-channel sparker profiles and 14 C ages of sediment cores reveals that the KSSM consists of three seismic units at the depocenter (>60 m thick): (i) the thin transgressive bottom (> ca 8000 cal bp ); (ii) thick (>40 m) obliquely progradational middle ( ca 8000– ca 2600 cal bp ); and (iii) thin transgressive top ( ca 2600 cal bp –present) units. The relative base level, predicted from the internal reflection pattern of the KSSM, remained significantly deeper (up to >70 m) than global sealevel during much of the Holocene. The apparent gradual drop (∼20 m) of the relative base level during the deposition of the middle unit, followed by a rise, further suggests that base level does not conform to sealevel and is more sensitive than the relative sealevel is to the local oceanographic regime and processes. 相似文献
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The effects of monochromatic (blue, yellow and red LED) and mixed wavelengths (fluorescent lamp) on the adsorption and absorption of Cu and Zn by Phaeodactylum tricornutum, Nitzschia sp., Skeletonema sp., and Chlorella vulgaris were investigated. In addition, we confirmed the potential of microalgae for phytoremediation of these heavy metals from contaminated marine sediment by using microcosm experiments that incorporated LEDs and semipermeable membrane (SPM) tube containing microalgae. Among the four microalgae, C. vulgaris grown under red LED exhibited the highest Cu and Zn removal with values of 17.5 × 10-15 g Cu/cell and 38.3 × 10-15 g Zn/cell, respectively. Thus, C. vulgaris could be a useful species for phytoremediation. In the microcosm experiments with SPM containing C. vulgaris, the highest Cu and Zn removal from sediment and interstitial water showed under red LED. Therefore, phytoremediation using LED and SPM tube containing microalgae could be utilized as an eco-friendly technique for remediating contaminated marine sediment. 相似文献
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The δD values of water and clay collected from 0.6 to 5.5 km deep wells in 9 oil and gas fields within the Houston salt basin located in the northeast Texas Gulf Coast were used to reevaluate the temperature dependence of hydrogen isotope fractionation between mixed layer illite/smectite (I/S) and water, and the equations of Yeh (1980), Geochim. Cosmochim. Acta, 42:140-143) and Capuano (1992), Geochim. Cosmochim. Acta, 56:2547-2554) for the calculation of αI/S-water, both of which are commonly cited in the literature. δD values of water and clay in the normally pressured and geopressured sections are different. In the normally pressured section (<2.6 km), δDwater is constant (−15 ± 1 (1σ)‰) while δDclay increases linearly from −59 to −43‰ with increasing depth. In contrast, in the geopressured section δDwater decreases linearly from −7 to −26‰ with increasing depth while δDclay is nearly constant (−36 ± 3 (1σ)‰). The opposite trends are a product of D/H exchange between clay and water in a water-dominated system within the normally pressured section and rock-dominated system in the geopressured section. Assuming hydrogen isotope equilibrium between sediments and enclosed pore water, the new δDwater and δDclay data were used to calculate the hydrogen isotope fractionation factor between I/S and water (αI/S-water), which showed a good fit to the equation derived by Capuano (1992), but not to the equation derived by Yeh (1980), both for the normally and geopressured data despite that both data sets are strikingly different. This suggests that hydrogen isotope equilibrium has been achieved in these two different regimes and that the equation by Capuano (1992) is valid and has wider applicability. 相似文献
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Chan Min Yoo Jongmin Joo Sang Hoon Lee Youngtak Ko Sang-Bum Chi Hyung Jeek Kim Inah Seo Kiseong Hyeong 《Ocean Science Journal》2018,53(2):381-394
A high level of confidence in resource data is a key prerequisite for conducting a reliable economic feasibility study in deep water seafloor mining. However, the acquisition of accurate resource data is difficult when employing traditional point-sampling methods to assess the resource potential of polymetallic nodules, given the vast size of the survey area and high spatial variability in nodule distribution. In this study, we analyzed high-resolution acoustic backscatter intensity images to estimate nodule abundance and increase confidence levels in nodule abundance data. We operated a 120 kHz deep-towed sidescan sonar (DSL-120) system (1×1 m resolution) across a 75 km2 representative area in the Korean Exploration Area for polymetallic nodules in the Northeastern Equatorial Pacific. A deep-towed camera system was also run along two tracks in the same area to estimate the abundance of polymetallic nodules on the seafloor. Backscatter data were classified into four facies based on intensity. The facies with the weakest and strongest backscatter intensities occurred in areas of high slope gradient and basement outcrops, respectively. The backscatter intensities of the two other facies correlated well with the nodule abundances estimated from still-camera images. A linear fit between backscatter intensity and mean nodule abundance for 10 zones in the study area yielded an excellent correlation (r2 = 0.97). This allowed us to compile a map of polymetallic nodule abundance that shows greater resolution than a map derived from the extrapolation of point-sampling data. Our preliminary analyses indicate that it is possible to greatly increase the confidence level of nodule resource data if the relationship between backscatter intensity and nodule abundance is reliably established. This approach has another key advantage over point sampling and image analyses in that detailed maps of mining obstacles along the seafloor are produced when acquiring data on the abundance of polymetallic nodules. The key limitation of this work is a poor correlation between nodule coverage, as observed from photographs, and nodule abundance. Significant additional ground truth sampling using well located box cores should be completed to determine whether or not there is a real correlation between the backscatter and abundance. 相似文献
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Sang Hoon Lee Jang J. Bahk Han J. Kim Kyung E. Lee Hyeong T. Jou Bong C. Suk 《Geo-Marine Letters》2010,30(2):133-142
The depositional characters of densely dated turbidite successions originating from the southwestern margin of the Ulleung
Basin reveal changes in high-resolution frequency, failing areas, and relative volumes of slope failures over the past 29.4
cal. ka. Between 29.4 and 19.1 cal. ka B.P., various thin- to very thick-bedded turbidites accumulated at an average recurrence
interval of ca. 605 years. After 19.1 cal. ka B.P., turbidites were deposited with an average recurrence interval of 3,183
years, and their thickness abruptly decreased upward. These features suggest that various-scale slope failures occurred frequently
during the eustatic lowering of sea level, and the frequency and relative volumes of slope failures suddenly decreased after
sea level began to rise. When sea level was lowest (20.0–19.1 cal. ka B.P.), successive stacks of very thick turbidites can
most likely be ascribed to larger-volume mass failures. An upward change from muddy to sandy turbidites around 21.4 cal. ka
B.P. suggests that the failing areas retrograded from the muddy upper-middle slope to the sandy uppermost slope when sea level
was nearly at its lowest. Based on these findings together with published evidence, frequent mass failures between 29.4 and
19.1 cal. ka B.P. were plausibly triggered by earthquakes, in combination with reduced hydrostatic pressure that promoted
gas-hydrate dissolution during the eustatic lowering of sea level. These data on the frequency, scale, failing areas, and
triggering causes of slope failures along the southwestern margin over the past 29.4 cal. ka, not documented in earlier studies,
provide invaluable information to better understand the basin-scale characters and occurrences of latest Quaternary slope
failures in the Ulleung Basin. 相似文献
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Ocean Science Journal - In this study, we examined whether phytoremediation using benthic microalgae (BMA) and a light emitting diode (LED) can remediate eutrophic sediments caused by promoting the... 相似文献